Kinect Sports games. Some who have left the British development studio have taken to Twitter under the moniker Mingy Jongo, and it's these folks who yearn to get back to the studio's roots: they want to get to work on a spiritual successor to Banjo-Tooie, the direct sequel to Banjo-Kazooie – a pair of 3D platformers published by Nintendo back in the N64 days.
The account sent out missives declaring this potential game would be a 3D platformer (natch) and that while this would be a "spiritual successor" to Rare's iconic series, Mingy Jongo says the goal "wouldn't be to try and recreate Banjo" but rather to create "something new." Microsoft owns the rights to the particular bear and backpack-bird in question, you see.
Kickstarter also came up as a means to fund this potential new game, and Mingy Jongo even suggested the Unity engine might be a good fit for maintaining the same "level of detail and googly eyes close to the original." But right now, all of this stuff is hypothetical ... until we see that Kickstarter page go live, anyway.